1. Field of the Invention
The present invention relates to pistons for internal combustion engines, particularly for automotive internal combustion engines.
2. Description of the Prior Art
Heretofore, lightweight and quiet operation have been required of automotive internal combustion engines. To meet this requirement, various improvements have been made particularly to a piston which is to transmit force of explosion to a crankshaft by way of a piston pin and a connecting rod. For example, a piston disclosed by Japanese Patent Provisional Publication No. 62-85152 is devised to have a skirt which is tapered toward an upper end and reduced in a bearing area with a view to improving both the durability and the lightweight characteristic.
However, the above described prior art piston is constructed so as to transmit side thrust to the cylinder wall by way of the skirt, so in case the piston skirt, particularly the lower section thereof posses a high rigidity vibrations of the piston are liable to be caused by the side thrust to result in a knocking noise known as "piston slap".